Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, USA.
J Am Chem Soc. 2010 Jan 20;132(2):580-6. doi: 10.1021/ja906917r.
Energy measures of the intra- and intermolecular electronic effects of triisopropylsilylethynyl substitution on pentacene have been obtained from the combination of closely related gas phase and solid phase ultraviolet photoelectron spectroscopy (UPS) measurements along with solution electrochemical measurements. The results show that the shift to lower ionization energy that is expected with this substitution and observed in the gas phase measurements becomes negligible in solution and is even reversed in the solid phase. The principles that emerge from this analysis are supported by electronic structure calculations at the density functional theory level. The relation between the gas phase and solid phase UPS measurements illustrated here provides a general approach to investigating the electronic effects acting on molecules in the condensed phase, which in this case are greater than the direct substituent electronic effects within the molecule. Electronic properties such as lower ionization energies built into the single-molecule building blocks of materials and devices may be reversed in the solid state.
已通过密切相关的气相和固相紫外光电子能谱（UPS）测量以及溶液电化学测量，获得了三异丙基硅乙炔基取代五并苯的分子内和分子间电子效应的能量度量。结果表明，预期的这种取代导致的电离能向较低能级的移动，在气相测量中观察到，但在溶液中变得微不足道，甚至在固相中发生反转。这种分析得出的原理得到了密度泛函理论水平的电子结构计算的支持。此处所示的气相和固相 UPS 测量之间的关系提供了一种研究凝聚相分子中电子效应的通用方法，在这种情况下，这些效应大于分子内的直接取代基电子效应。材料和器件中单分子构建块中内置的较低电离能等电子性质在固态中可能会发生反转。
